In an embedded processor such as a digital signal processor (DSP), internal memory is costly and precious. Most of the processors have little internal memory, typically barely sufficient for a minimal operating system or critical portion of code that is executed frequently. The internal memory in the DSP is not usual known to the typical user. If an application running on the DSP is processing multiple channels of multimedia, for example voice, video or audio, channel specific buffers typically reside in a memory that is external to the DSP. The data is paged into the internal memory when the application layer processes the channel.
Also, data in the external memory can be accessed through a cache. In a conventional DSP, when a cache miss happens, a cache width worth of data (also referred to as a cache line) is accessed.